Hose Clamp With Flat Spring Liner

ABSTRACT

An improved hose clamp having an annular band having an inner face, tensioning means, and an annular spring liner; the spring liner having a circumferential shoulder near an edge of the liner; and a central, cylindrical, flat, contact portion of smaller circumference than the shoulder, and of smaller width than the inner face of the band. The shoulder is adapted to abut the inner face and the contact portion is adapted to contact a hose or other article to be clamped.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of hose clamp assemblies,more particularly to a spring liner that is associated with a hose clampassembly, and specifically to a spring liner with a central, flat,hose-contact portion.

2. Description of the Prior Art

Hose clamps are commonly utilized to join together hoses and fittings orconnectors (referred to hereinafter as fittings), for example, withinthe automotive industry. Hose clamps, hose and fittings respond tochanges in ambient temperature and system temperatures based on thethermal properties of the aforementioned components. Differingcoefficients of thermal expansion of these components can result inthermally-induced reductions in clamping force, thus creating thepotential for fluid or gas leakage. In addition, changes in elasticityof the hose materials over time due to creep, compression set, ordeterioration can also reduce the clamping force and create thepotential for fluid leakage.

Various types of spring liners used in conjunction with hose clamps areknown. U.S. Pat. Nos. 7,178,204 and 7,302,741 are exemplary of the art,disclosing a spring liner having two inward projecting ridges with anoutward-projecting ridge in between. The ridges create two zones of veryhigh compression in the hose, while the central ridge area creates azone of lesser compression.

Mention is also made of a co-pending application by the same applicanttitled “Hose Clamp With Rippled Spring Liner,” filed on the same day asthe present application, the contents of which are hereby incorporatedherein by reference.

SUMMARY

It is an aspect of the present invention to provide an improved springliner which allows a hose clamp to self-compensate for changes inelastic properties and diametric changes of the underlying hose andfittings. The invention is directed to an annular spring liner for ahose clamp having a circumferential shoulder near each edge of the linerand a central inwardly-directed circumferential, cylindrical ridge withflat contact portion there between the two shoulders. The hose clampseats on the shoulders of the liner when the clamp is tensioned. Thus,at least after assembly, and before tensioning of the hose clamp, theflat central ridge is separated from the inner face of the tensioningband of the hose clamp by a gap of constant thickness. The width of theflat contact portion is less than the width of the inner face of thetensioning band. The width of the flat contact portion may be in therange from 40% to 75% of the width of the inner face of the tensioningband.

In another embodiment of the invention, the spring liner further has onat least a portion of one or both circumferential edges a radiallyoutwardly-flared flange.

It is another aspect of the present invention to provide an improvedhose clamp assembly having an annular band having an inner face, atensioner disposed to facilitate constriction of the band, and theannular spring liner as described above.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims. The novel features which are believed to be characteristic ofthe invention, both as to its organization and method of operation,together with further objects and advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form part ofthe specification in which like numerals designate like parts,illustrate embodiments of the present invention and together with thedescription, serve to explain the principles of the invention. In thedrawings:

FIG. 1 is a perspective exploded view of a hose clamp assembly includingclamp and spring liner in accordance with an embodiment of the presentinvention;

FIG. 2 is a partial sectional view of the spring liner of FIG. 1, takenalong section 2-2;

FIG. 3 is a partially fragmented view of a hose clamp assembly includingspring liner, hose, and fitting in accordance with an embodiment of thepresent invention; and

FIG. 4 is a graph of clamp pressure versus position around a hose for anembodiment of the invention and for two comparative examples.

DETAILED DESCRIPTION

The present invention provides a means of reducing the contact surfacearea of the inside diameter (ID) of traditional worm-gear hose clamp inorder to increase the unit loading the hose clamp assembly imparts tothe underlying hose or substrate. The reduction in contact surface areais achieved by the use of a circular liner that is inserted into the IDof a hose clamp or tensioning band 1. The cross-section of the liner hasshoulders 5 with contact surfaces on their outside diameter (OD) whichare together approximately equal in axial extent (width) to the insidesurface width of the hose clamp or tensioning band. The edges of theshoulders may project upward towards the hose clamp or tensioning bandat angles to hold the liner captive within the hose clamp or tensioningband ID. The profile of the liner also includes a flat, cylindricalcontact portion 7 positioned inward or lower than shoulders 5. Bycontact is meant that flat portion 7 is intended to contact theunderlying hose or substrate. This surface is narrower than the hoseclamp or tensioning band 1 width and may be in the range of 40% to 75%of the hose clamp or tensioning band width. Two legs 6 bridge betweenthe two shoulders and the lower contact portion 7 of the liner. Theselegs may be symmetrical and are located on either side of the lowercontact surface and project outward at acute angles relative to theclamp centerline, thus reaching to and attaching to the upper shoulders.

The increase in unit loading can also be described as an increase in theradial pressure the clamp exerts on the underlying hose or substrate.The radial pressure (p_(r)) a hose clamp or a tensioned band exerts is afunction of the band tension (T), the band width (w) and the clampingdiameter (d). For any fixed value of “T” and “d”, an increase in “w”will decrease radial pressure, and a decrease in “w” will increaseradial pressure. Manipulation of a simplified hoop stress formula candemonstrate this behavior; 2T=p_(r) w d transposes to p_(r)=2T/(w d).

In addition to increasing a hose clamp or tension bands' radial pressureas a result of the liner's narrower contact width, the liner also canact as a spring, thus providing a thermal-compensating feature for theclamp. The spring effect will be described in more detail later. First,the drawings will be discussed in more detail.

Referring to FIG. 1, a hose clamp is shown comprising an outer annularband 1, and a typical tensioning means 3, 4. FIG. 1 also shows inexploded view flat spring liner 9 in accordance with the presentinvention. In another embodiment, spring liner 19 is shown in section inFIG. 2. Spring liner 9, as well as spring liner 19, is an annular ringwith overlapping ends 10. Spring liner 9 and 19 comprise two flatannular circumferential shoulders 5 near the edges of the liner, a flatcentral annular circumferential contact portion 7 located between thetwo shoulders 5 and of smaller circumference than the shoulders, and twoannular circumferential legs 6 there between connecting the inner edgesof shoulders 5 to the outer edges of flat contact portion 7. FIG. 2shows radial height differential A between the two shoulders 5 and theflat contact portion 7. When liner 9 or 19 is inserted into clamp band1, the inner face of band 1 will abut or seat on shoulders 5, and gap Awill result between the outer surface of contact portion 7 and the innerface of band 1 in the absence of clamp tensioning forces. Thus, flatportion 7 does not abut the inner face of band 1 in the absence of clamptensioning forces.

The terms outward and inward refer to direction with respect to thecenter axis of the generally circular liner. Inward means directedtoward the center axis of the liner. Outward means directed away fromthe center axis of the liner.

Upon applying clamp tensioning forces, i.e., tightening or tensioning ofthe band, the overlap section 10 of the liner can increase in length,resulting in a decrease in the circumference of the liner. As the bandtightens, the liner is thus pulled into compressive engagement with theassociated hose. FIG. 3 illustrates the hose clamp assembly in use witha hose 11 and a hose fitting 12. Band 1 of the hose clamp seats on twoshoulders 5. The inward facing flat contact portion 7 of the linercreates a zone of relatively uniform compression 14 in the hose.

The profile of the liner is designed so that the two legs 6 can deflectunder the compressive forces, creating a spring effect. As the band istensioned, the deflection of the legs will cause gap A to decrease to A′(A′≦A), or perhaps even disappear completely. As the band is tensioned,the deflection may also cause the flat contact surface to deformslightly. The decrease in gap is an indication of the amount of springenergy stored in the annular spring liner. The net effect of theseradial and axial deflections and the resulting compression forces on thehose is a much better initial and long term sealing effect than obtainedwith prior art hose clamp liner designs.

As the hose and clamp assembly is exposed to thermal fluctuations, thespring liner can respond by further deflecting or by relaxing, thushelping to maintain an excellent sealing force on the hose assembly. Asthe hose material, which is typically vulcanized rubber, takes on acompression set, or inelastic deformation, due to deterioration ofelastic properties over time, the force exerted by the rubber will relaxor decline, and the spring liner again relaxes or releases some of thestored spring energy, thus maintaining an excellent sealing force on thehose. Compared to prior liner designs with narrow ridges which createzones of very high compression, the present invention creates a moreuniform zone of moderate compression, which may advantageously avoidextreme deformations and extreme effects of compression set in therubber hose being clamped.

If the hose clamp is tensioned to the extent that gap A′ is eliminatedand the outer surface of contact portion 7 contacts the inner surface ofband 1, then any further deflection of the spring liner requires muchhigher forces, commensurate with a dramatic increase in spring rate.Under this condition, the deflection of the spring liner in response tothermal expansion of the hose is very limited. However, under thiscondition, the spring liner's ability to relax or respond to thermalcontraction of the hose is maximized. Thus, the clamp and spring linermay be designed so that in use, gap A′ is maintained even in thepresence of clamp tensioning forces. Alternately, the clamp and springliner may be designed so that in use, the outer surface of the flatcontact portion 7 may abut the inner face of the hose clamp 1 in thepresence of clamp tensioning forces.

As shown in FIG's 2 and 3, spring liner 19 may also have one or tworadially outward flared flanges 8 to aid in aligning liner 19 withinband 1. The flanges shown in the figures flare outward at about a 45°angle. Any suitable flare angle or flare shape may be used. Flanges 8,as well as legs 6, may be sharply bent or may have a more rounded,gradual transition from adjoining shoulders 5 or contact portion 7.Flanges 8 may extend the entire circumference of the liner or may be cutshort in appropriate places to reduce interference in the overlapsection 10 of the liner or to reduce interference between the liner andthe tensioning means 3, 4. Alternately, or in addition to a flange, thespring liner may be more or less permanently affixed to band 1 by anymeans that provides an adequate bond, such as, but not limited to, heatwelding, chemical welding, chemical bonding, staking, mechanicalfasteners, or a combination of two or more of the foregoing.

The spring force exerted by the liner depends on the thickness andmodulus of the material of which it is constructed. The force alsodepends on the precise profile, i.e. the shape and size of the legs,contact portion, and shoulders. The profile shown in FIG. 2, when formedout of sheet metal about 0.012 inches (0.3 mm) thick, is suitable fortypical automotive hose clamping applications. One skilled in the artwould be able to alter the materials, material properties, shoulder andflat surface dimensions, flange angles, overlap distance, and/or springliner thickness to optimize the flat spring liner for particularapplications. The profile need not be perfectly symmetric. The twoshoulders, the legs, and the central flat surface may all be ofdifferent sizes. The central flat surface need not be at the exactcenter of the annular liner. The two leg angles may be different. Thethickness of the liner may also vary in the axial direction.

The shoulders need not be broad, flat structures. A shoulder orshoulders may be a circumferential line of contact adapted to abut theinner face of the band of the hose clamp. Such a shoulder could be anoutwardly convex ridge formed near the edge of the liner, or it couldsimply be an edge of the liner. The important feature of the shoulder isthat it be adapted to contact or abut the inner face of the band of thehose clamp. Viewed in section as in FIG. 3, the contact between theinner face of the band 1 and the shoulder 5 could therefore be a pointor a line. In three dimensional terms, the contact between the innerface of the band 1 and the shoulder 5 could therefore be a circular lineor a cylindrical area, depending on the shape of the shoulder.

Friction between the overlapping ends of the spring liner can affect theclamping force achieved during assembly. To reduce the friction force,the overlapping ends may be coated with wax or other suitable lubricant.To increase the friction force, the overlapping section may be cleaned,roughened, grooved, knurled, or the like. Thus, one skilled in the artcan optimize the friction as needed or desired.

Any of the various hose clamp tightening or tensioning means, i.e.,“tensioner,” known in the art may be used. By way of illustration, thetensioning mechanism may be a worm drive 3, 4 as shown in FIG. 1.Alternatively, the tensioner may be a T-bolt, a ratcheting mechanism, abolt and barrel mechanism, a nut and bolt assembly, a permanent crimp,or the like, or combinations thereof. Alternatively, the clamp may be anendless band with thermally frozen-in strain, which is tensioned byreleasing the strain and allowing the band to shrink onto the springliner, hose and fitting. In addition, tensioning band or hose clampwidth may vary. The proportionality of tensioning band width to linerwidth and liner contact width may vary.

Other known features of hose clamps may be incorporated if desiredwithout departing from the scope of the invention. For example, variousmeans of attaching the assembly to the hose, such as adhesive, avulcanizing patch, a locating tab, a locating clip, and the like may beincorporated. Cutouts or apertures for adjusting spring stiffness, orthe like may be incorporated.

In actual practice, a hose clamp with an annular spring liner is placedover the hose and fitting to be joined. Clamp diameter is reduced bymeans of the tensioning mechanism. Spring liner diameter is reducedproportionally to the clamp diameter reduction by increasing thecircumferential overlap length of the liner. As the combined hose clampand annular spring liner diameters decrease, radial pressure acting onthe underlying hose and fitting increase. Because of the shape of theliner, the radial pressure on the hose is amplified from that generatedby the clamp alone, while remaining relatively uniform in the hoseregion under the liner.

As the radial forces acting on the spring liner increase as a result ofincreased tension in the outer band, the spring liner deflects in such amanner that the shoulders 5 deflect downward towards the hose 11. Thismovement can continue until the desired tension is achieved. However,the movement becomes limited at the point where the central flat portion7 contacts (if ever) the inner face of the clamp band 1. The deflectionsare elastic, spring-like behavior. Therefore, the liner can respond tovariations in band tension and/or radial pressures as a spring. Thisspring behavior insures that the central flat portion 7 exertssufficient radial pressure on the hose throughout the life of the clampinstallation.

As an example of a possible modification, it is envisioned that in oneembodiment of the invention, the inner face of the hose clamp couldinitially when assembled contact one shoulder of the spring liner, therebeing a gap between the inner face of the clamp and a second shoulder ofthe liner. As the hose clamp of this embodiment is tensioned, the gapbetween the inner face and the second shoulder would close asdeformation energy is stored in the spring liner, with the clamp perhapseven finally seating on the second shoulder.

The following examples illustrate the use and benefits of an embodimentof the invention. For the examples, a hose clamp with worm drivetensioning as shown in FIG. 1 was obtained. The band had a width of0.405 inches (10.3 mm) and a nominal diameter of about two and a halfinches (about 65 mm). As an inventive example, a spring liner as shownin FIG. 2 was also constructed, having a total width of 0.47 inches(11.9 mm) and a width of contact portion 7 of 0.165 inches (4.2 mm), andthis was used with the aforementioned hose clamp. As comparative example1, the hose clamp was used without a spring liner. As comparativeexample 2, a spring liner having two inward ridges according to U.S.Pat. No. 7,302,741, FIG. 2, was constructed with similar total width andused with the hose clamp.

The three examples were in turn applied to a reinforced rubber hose ofabout 2.25-inch internal diameter in which a smooth cylindrical mandrelor fitting was inserted. Between the mandrel and hose, a film-typepressure sensor was inserted. The pressure profile between hose andmandrel was recorded at about 31 positions in the circumferentialdirection by 44 positions in the axial direction, and the averagepressure for the positions located directly under the liner wascalculated and compared on a normalized basis. The same torque of 30in-lbs (3.4 N-m) was applied to the worm drive for the inventive exampleand for comparative examples 1 and 2. The results of this comparison arepresented in Table 1. Smoothed pressure profiles for this comparison areshown in FIG. 4. The Comparative Examples are abbreviated as “Comp. Ex.”In FIG. 4. The profiles in FIG. 4 were smoothed by averaging all thepositions along the axial direction at each of the 31 circumferentialpositions. Then seven groups of four and one group of three sequentialdata points of circumferential data were averaged resulting in eightdata points for the smoothed circumferential pressure profiles shown inFIG. 4.

TABLE 1 Inventive Comparative Ex. 1 Comparative Ex. 2 Example No LinerPrior art Liner Average Pressure 142 100 105 (normalized)

The results in Table 1 and FIG. 4 illustrate various advantages of theinventive spring liner. The average pressure results shown in Table 1illustrate how the spring liner can amplify the clamp force to increasethe radial sealing pressure. The 42% increase in average pressure overthe clamp with no liner is, however, less than one would predict fromthe width difference of the inventive liner compared to the band. Thisshort fall is believed due to edge effects and relaxation or compressionset effects within the rubber. As such, the particular advantagesexhibited may be dependent on the details of the hose construction andmaterials which is being clamped. Thus, the benefits of the invention,and the comparative advantages relative to the prior art liner, maydepend on the type of hose and the type of application. The prior artliner, with its two ridges may still give higher peak pressuresimmediately under the ridges. However, some types of hose or applicationmay be better clamped with a higher average pressure, but lower peakpressure.

In FIG. 4, it can be seen that the clamp pressure for the inventiveexample is higher than the comparative examples for the entirecircumference. This should translate to improved sealing performance forthe inventive example. FIG. 4 also illustrates that the flat springliner provides more uniform distribution of pressure around the clampcircumference than the comparative example with no liner. The variationin the region of the worm-drive housing (near position 5 in FIG. 4) issignificantly less when a liner is used than without a liner. This tooshould translate to improved sealing performance.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions, andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods, and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps. The invention disclosed herein may suitably bepracticed in the absence of any element that is not specificallydisclosed herein.

1. An annular spring liner, for a hose clamp having an inner face,comprising: a circumferential shoulder near an edge of said liner; and acentral, cylindrical, flat, contact portion of smaller circumferencethan said shoulder; wherein said shoulder is adapted to abut said innerface.
 2. The spring liner of claim 1 further comprising acircumferential shoulder near each edge of said liner, wherein both saidshoulders abut said inner face.
 3. The spring liner of claim 2 whereinsaid flat contact portion does not abut said inner face in the absenceof clamp tensioning forces.
 4. The spring liner of claim 3 wherein saidflat contact portion is narrower than said inner face.
 5. The springliner of claim 4 wherein said flat contact portion has a width in therange of 40% to 70% of the width of said inner face.
 6. The spring linerof claim 4, further comprising on at least one edge a radially outwardlyflared flange.
 7. The spring liner of claim 3, further comprising oneach circumferential edge a radially outwardly flared flange extendingbeyond the width of the inner face.
 8. The spring liner of claim 1wherein said liner has generally circular shape with overlapping ends.9. A hose clamp having an inner face and an annular spring liner, saidliner comprising: a circumferential shoulder near an edge of said liner;and a central, cylindrical, flat, contact portion of smallercircumference than said shoulder; wherein said shoulder is adapted toabut said inner face.
 10. The hose clamp of claim 9 further comprising acircumferential shoulder near each edge of said liner, wherein both saidshoulders abut said inner face.
 11. The hose clamp of claim 10 whereinsaid flat contact portion does not abut said inner face in the absenceof clamp tensioning forces and a gap is defined there between.
 12. Thehose clamp of claim 11 wherein said flat contact portion is narrowerthan said inner face.
 13. The hose clamp of claim 12 wherein said flatcontact portion has a width in the range of 40% to 70% of the width ofsaid inner face.
 14. The hose clamp of claim 12, further comprising onat least one edge a radially outwardly flared flange.
 15. The hose clampof claim 13, further comprising on each circumferential edge a radiallyoutwardly flared flange extending beyond the width of the inner face.16. The hose clamp of claim 10 wherein said liner has generally circularshape with overlapping ends.
 17. The hose clamp of claim 13 furthercomprising a tensioner.
 18. The hose clamp of claim 17 wherein saidtensioner comprises a worm drive.
 19. The hose clamp of claim 17 whereinsaid liner deflects elastically under a clamp tensioning force so thatsaid gap varies with said clamp tensioning force.